Plastic triglyceride shortening compositions are commonly aerated with an innocuous gas such as nitrogen or air. By incorporating an aerating gas into the shortening in the form of uniformly dispersed very small bubbles, a white opaque product of pleasing appearance is obtained. Additionally, aeration can lead to a softer product with an extended plastic range (i.e. the temperature range over which the product deforms easily without being fluid).
Conventional methods for producing plastic shortenings involve the steps of heating the shortening to a temperature above the melting point of its solid components to form a liquid fat, rapidly chilling the liquid fat in a scraped surface heat exchanger to produce crystal nuclei, passing the fat through a crystallizing unit where crystallization is allowed to continue with mild agitation, and storing at constant temperature in a final crystallization step known as tempering. The aerating gas is injected into the fat prior to the chilling process and the fat is maintained under high pressure during the chilling and subsequent crystallization stage so that the injected gas is maintained in solution during these processes. After leaving the crystallizing unit the fat is passed through a suitable throttle valve where the pressure is released and the dissolved gas comes out of solution and is dispersed as minute bubbles.
The amount of gas which can be incorporated into plastic triglyceride shortening by the conventional process described above is limited. Although up to about 22 volume percent of gas can be incorporated in shortening by the conventional process, high levels of gas (e.g., 15%-22%) can give a coarse dispersion or a streaked product.
It would be desirable to incorporate higher levels of gas into shortenings and other fatty compositions for several reasons. Increased aeration of such a composition will decrease the net weight per unit volume that a person ingests, thereby reducing the number of calories. Additionally, such a composition will be more economical to produce, and it will have a light, fluffy texture.
Certain types of icings, generally known as cream or butter-cream icings, contain a substantial proportion of triglyceride fat or shortening and can be whipped to incorporate an appreciable volume of air or nitrogen. Although such icings initially have an attractive appearance and structure, they frequently tend to be unstable over relatively short periods of time. That is, they are subject to excessive drying, firming, or hardening, and tend to bleed oil, slump or collapse.
There have been various attempts to solve the problems related to highly aerated shortenings and highly aerated shortening-containing icings. For example, U.S. Pat. 3,549,387 of Howard, issued Dec. 22, 1970, discloses a special process for preparing aerated plastic shortenings in which gas is introduced into the shortening after the tempering step, instead of prior to the chilling step. The product, which can contain between 5% and 50% by volume of air, is said to have improved creaming properties.
U.S. Pat. No. 3,253,928 of Bedenk et al., issued May 31, 1966, discloses improved aerated cream icings. The icings are prepared by employing a plastic shortening made from a mixture of partially hydrogenated triglyceride and substantially completely hydrogenated triglyceride hardstock having a predominant beta-phase crystalline structure.
However, there is still a need for further improvement in aerated shortenings, cream icings, and other fatty compositions. One reason is that triglyceride fats are very high in calories. A triglyceride shortening containing up to 50% by volume of air, as described in the Howard patent, will still contain a considerable number of calories. It would be desirable to make an aerated fatty composition that is lower in calories by a reduction in the amount of triglyceride fat and also by an ability to hold more than 50% by volume of air.
Sugar and sugar alcohol fatty acid polyesters are known in the art as a low calorie replacement for normal triglyceride fat in food products. U.S. Pat. No. 3,600,186 of Mattson et al., issued August 17, 1971, discloses the use of sugar and sugar alcohol fatty acid polyesters as a fat replacement in foods such as shortenings, margarines, mayonnaise, and salad or cooking oils. Highly aerated fatty compositions are not mentioned.
It is an object of the present invention to provide a highly aerated, low calorie fatty composition.
It is also an object of the present invention to provide reduced calorie, highly aerated fatty composition-containing food products which are shelf stable and resistant to slump and collapse.
These and other objects of the present invention will become evident from the disclosure herein.
All parts, percentages and ratios used herein are by weight unless otherwise indicated.